Turbochargers, which are superchargers that perform supercharging of an engine, drive a turbine utilizing exhaust gas. The turbochargers have a waste gate mechanism that detours the exhaust gas in order to prevent damage resulting from supercharging pressure becoming too high. The waste gate mechanism can cause the exhaust gas to flow to a system exterior without going through the turbine by opening the waste gate valve. Accordingly, the flow rate of the exhaust gas that flows into the turbine can be reduced in accordance with an opening degree of the waste gate valve (refer to Patent Document 1). As the waste gate mechanism, a flap-type waste gate valve is used in many cases.